The present invention relates to techniques for controlling functionality of devices and more particularly to techniques for enabling devices to be added to device families and for providing a tangible paper-based confirmation of the membership.
Recent years have seen a proliferation in the use of devices of different types including printers, cameras, copiers, scanners, facsimile machines, phones, various hand-held devices such as cellular phones, personal data assistants (PDAs), etc., and other types of devices. Enabling communication between these devices is an area of growing technological importance. With the advent of wireless communication, many of these devices communicate with each other using wireless communication protocols, although other communication protocols may also be used. With the growing emphasis on data integrity and security, it is often desired that communications between devices be performed in a secure manner. This is especially important in a wireless communication environment to prevent or make it difficult for eavesdroppers to listen in on wireless communication sessions.
Encryption schemes are typically used to ensure secure communications. These encryption schemes generally involve the use of encryption keys (e.g., public/private encryption keys). In order to enable secure communication between two devices, appropriate encryption keys are exchanged between the devices. These encryption keys are then used to enable secure communication between the devices. Generally, to enable secure communication between a pair of devices, each device is given one or more keys specific to the other device to enable communication with the other device. The process of choosing encryption keys which allows two devices to communicate is commonly referred to as device pairing, since each pair of devices is given a distinct set of keys to enable communication between the devices. A device generally has a distinct set of keys for each device with which the device wants to engage in secure communications.
Device pairing is feasible and works well for a small number of devices. However, since the number of pairings rises with the square of the number of devices, as the number of devices increases, the number of pairings rapidly increases and becomes unmanageable and impractical. For example, 4950 pairings are needed for 100 devices. Accordingly, if we envision an office with hundreds or even thousands of devices, the use of device pairings is no longer practical.